The present invention concerns a device for monitoring the tires of a vehicle, and more precisely a device comprised of, for each wheel, an electromechanical module connected to a rotating antenna, and, coupled to the latter, a stationary antenna connected to a central unit of the vehicle.
It is known that monitoring the pressure and temperature of tires is essential for proper safety; in addition, if this monitoring is done continuously during utilization of the vehicle, added to increased safety is an extension of the service life of the tires, a decrease in consumption of fuel, an improvement in road-holding and comfort, etc.
The requester has developed over about the last ten years such a system of continuous monitoring, known under the name of "MTM" ("Michelin Tire Monitor"), which has proven itself in some very harsh automobile races. Briefly, this system is composed of a central unit powered by the battery of the vehicle, this unit being connected, for each wheel, to a stationary antenna; on each of the wheels is mounted a rotating antenna connected to a module comprised of a pressure sensor as well as a temperature sensor; electromagnetic coupling is established between the antennas in pairs; this coupling allows on the one hand to transmit energy from the central unit to each wheel module and, on the other hand, to transmit to the central unit the signals gathered from each sensor, these exchanges being made continuously according to specific rates.
This basic system has already given rise to improvements and adaptations. For example, patent FR 2 706 811 describes the case of a truck equipped with wheels mounted in single and duals, on which one of the lug nuts is used to connect the sensor of tire pressure and the wheel module to the rotating antenna.
We can also cite patent U.S. Pat. No. 5,235,850 (Texas Instruments) which implements for each wheel to be monitored a rotating part (rotor) connected to the measurement sensors, and a stationary part (stator) connected to a central unit, these parts being coupled by two rotating and stationary antennas of which one is annular.
But these known systems all present a disadvantage: they require a rotating annular antenna comprised of an annular coil made to measure for each type of wheel, which complicates the installation of these monitoring devices and which greatly increases their cost. The requester has therefore had the unexpected idea of eliminating the annular coil from this rotating antenna.